The present invention relates to a headframe for use with a stereotactic system. More particularly, it relates to a surgical headframe for accurate, non-traumatic (non-invasive) positioning (fixation) of a reference frame to a patient as part of a stereotactic system, especially a tandem optical stereotactic device.
Stereotactic surgical systems provide surgeons with visual guidance information of surgical instruments/probes relative to an enclosed anatomical position, especially within the cranium or head. Basically, a stereotactic surgical system provides a quantitative determination of an anatomical position based upon a scanned image, such as a CAT scan, MRI scan, PET scan, etc. This scanned information is processed by a computer to produce a displayable image of the head. Subsequently, during a surgical procedure, the stereotactic system relates a position of a surgical instrument otherwise deployed within the anatomical body of interest (e.g., the head) relative to the previously-generated scanned information in visual form.
Stereotactic devices are highly useful in the field of neurosurgery, and more recently ENT procedures requiring instrument deployment in close proximity to the optic nerve, carotid artery, skull base, facial nerve, internal auditory canal, etc. A more recent stereotactic system is optical or camera based in which two cameras are employed to visualize special instruments in a surgical field, digitize the viewed information from the camera and relate it via computer graphics to image data generated by the above-described image scanning techniques. The relationship of the optical camera(s) view and the image data will then make quantitative the anatomy seen in the camera view and also make quantitative the position of surgical instruments such as probes, microscopes, or space pointers, etc., relative to the anatomy via registration of the camera view to the image data. An example of such a tandem optical, stereotactic device is available under the trade name Landmar(trademark) ENT Image Guidance System, from Medtronic-Xomed of Jacksonville, Fla.
Regardless of the exact stereotactic configuration, a stereotactic or dynamic reference frame must be fixed to the patient""s head to provide accurate positioning information. A wide variety of headframes or headframes have been developed to facilitate fixation of the reference frame to the patient""s head. In this regard, important constraints relating to the headframe design include precise positioning of the reference frame relative to the patient""s head, relatively long-term fixation, and allowing for movement of the patient""s head without deviation of a position of the reference frame relative to the head during the surgical procedure. In light of these constraints, many of the available stereotactic headframes incorporate one or more bone screws or bone pins to physically secure the headframe to the skull. Obviously, this is highly invasive, and contrary to the minimally invasive nature of intended procedures. Alternatively, other stereotactic headframes are tightly clamped to the patient""s head. Due to the possibility of headframe movement along the patient""s skin, the clamping device(s) is typically very rigid, again causing discomfort to the patient under extended usage.
Surgical stereotactic systems continue to rapidly evolve with improvements to imaging and display components. However, the headframe apparatus has essentially remained unchanged, and is unacceptably bulky and invasive or traumatic. Therefore, a need exists for an improved surgical headframe for use with a stereotactic system.
One aspect of the present invention provides a surgical headframe for maintaining a stereotactic system reference frame relative to a patient""s head. The headframe includes a frame body, first and second arms, a plurality of contact pads, and a strap. The first and second arms extend from opposing sides of the frame body, respectively. The plurality of contact pads are coupled to the frame body and are each adapted to engage a patient""s head. Finally, the strap is selectively connectible to the first and second arms. In this regard, the strap is adapted for wrapping about a back of a patient""s head. With this construction, the surgical headframe is capable of precisely positioning and fixating the reference frame to the patient""s head during a stereotactic procedure, without requiring bone screws, bone pins or clamps. In one preferred embodiment, three contact pads are provided, and are arranged in a tripod-like fashion. In a further preferred embodiment, the contact pads are pivotally coupled to the frame body, and are co-planer. With this preferred construction, the headframe is highly stable when applied to the patient""s head. In yet another preferred embodiment, a control pad is mounted to the frame body.
Yet another aspect of the present invention relates to a method of securing a reference frame to a patient""s head as part of a surgical procedure. The method includes providing a surgical headframe having a frame body, first and second arms, a plurality of contact pads, and a strap. The first and second arms extend from opposing sides of the frame body. The contact pads are coupled to the frame body. Finally, the strap is selectively securable to the first and second arms. With this in mind, the reference frame is mounted to the headframe. The headframe is then positioned at the patient""s head such that the contact pads contact the patient""s head. The strap is then wrapped behind the patient""s head. Finally, the strap is secured to the first and second arms. In one preferred embodiment, the first and second arms are rotatably mounted to the frame body, thereby reducing moment forces generated by extension of the strap about the patient""s head from being transmitted to the patient""s forehead and serve to increase user comfort.
Yet another aspect of the present invention relates to a method of manufacturing a surgical headframe for use in a stereotactic procedure. The method includes providing a frame body having a central portion and opposing sides. First and second arms are extended from the opposing sides of the frame body, respectively. A plurality of contact pads are coupled to the frame body. In this regard, each of the contact pads are adapted to engage a patient""s head. Finally, a strap is selectively secured to the first and second arms opposite the frame body. To this end, the strap is adapted for wrapping about a back of a patient""s head. Upon final assembly, the headframe is adapted to receive and maintain a stereotactic reference frame. In one preferred embodiment, a first contact pad is coupled to the central portion of the frame body, and the second and third contact pads are positioned opposite one another relative to the first contact pad.